Apparatus for shot-peening turbine blades

ABSTRACT

A turntable having a number of pairs of apposed resilient gripping members mounted on nested ring members, one of the rings having its axis eccentrically translatable relative to the other, the translatable ring being pressure-biased in one direction transversely to its axis so that the space between the rings is greater at one end of a diameter to allow loading of workpieces between gripping members, the space closing with rotation of the rings to provide a firm grip of the workpieces passing through a subsequent peening zone, a portion of each workpiece being exposed to peening action and a portion shielded therefrom.

United States Patent Morris APPARATUS FOR SHOT-PEENING TURBINE BLADES451 June 13, 1972 Priniary Eraminer-Charles W. Lanham AssistantExaminer-Gene P. Crosby Attomey-Raymond P. Wallace and Victor D. BehnABSTRACT A turntable having a number of pairs of apposed resilientgripping members mounted on nested ring members, one of the rings havingits axis eccentrically translatable relative to the other, thetranslatable ring being pressure-biased in one direction transversely toits axis so that the space between the rings is greater at one end of adiameter to allow loading of workpieces between gripping menibers, thespace closing with rotation of the rings to provide a firm grip of theworkpieces passing through a subsequent peening zone, a portion of eachworkpiece being exposed to peening action and a portion shieldedtherefrom.

7 Claims, 3 Drawing Figures PATENTEnJuu 13 m2 sum 10F 2 INVENTORBACKGROUND OF THE INVENTION This invention relates to apparatus forshot-peening portions of a workpiece while shielding other portions, andmore particularly to such apparatus wherein the airfoil portion of aturbine blade is masked from the peening operation while the rootportion is being peened.

In the prior art it is known to provide a turntable having a pluralityof apertures therein, in each of which apertures is disposed a rubbercylinder having a socket therein of airfoil configuration, of a size andshape to accept the airfoil section of the blade to be peened. Anoperator at one side of the turntable thrusts a blade into each socket,leaving the root portion exposed. The turntable, rotating eitherintermittently or continuously, then carries the blade through aflexible curtain into a cabinet where appropriate nozzles direct metalshot or glass beads or other peening material against the exposed rootportion.

Such an arrangement requires expensive tooling, in that each rubbercylinder must be molded with a blade socket of the correct size andshape for the blade being peened. If

blades of another size or shape are to be processed, another set ofcylinders must be provided. Furthermore, since turbine blades have atwist in the airfoil portion, the sockets in the cylinders must have acorresponding twist, and the blades must be inserted by the operatorwith a twisting motion. This makes for slow loading of the cylinders anda low production rate, since the blade must be pushed fully into thesocket in order to leave no portion of the airfoilsection exposed to thepeening material.

SUMMARY OF THE INVENTION The present invention provides a turntablehaving as portions thereof two ring members one inside .the other, therings bearing on their apposed surfaces a plurality of pairs ofcircumferentially disposed gripping members of rubber or other resilientmaterial. One of the rings has its center of the turntable axis and isfixed to the turntable for rotation therewith. The other ring is keyedto the turntable so that it rotates therewith, but in such a manner thatit is to some degree slidable across the diameter of the turntable, andtherefore its axis of rotation is somewhat displaced from the axis ofthe other ring. Biasing means is provided so that the slidable ring isconstantly biased toward one side of the turntable. Thus, as themechanism turns, the spacing between the ring members and their pairedgripping members is always greater on one side of the turntable, whichis the loading station. At the loading station blades are inserted withthe airfoil section between the gripping members, the space therebetweenbeing sufficient for insertion without great effort or severe friction.The roots of the blades protrude above the gripping members for exposureto peening, and the airfoil sections are shielded from the peeningmaterial between the rings. As the apparatus turns, with one ringconstantly biased off center, the space therebetween narrows and gripsthe blades firmly between the resilient members as the blades enter thepeening cabinet through the flexible curtain. As the rings rotatethrough the peening section, the blade roots remain above the grippingmembers and are exposed to the peening process, and the airfoil portionsbetween the rings are shielded from stray peening material.

Since the gripping members are elements of simple form, the cylinders ofthe prior art having precisely shaped sockets are no longer necessary,and the cost of the tooling is greatly reduced. Since the machine can beeasily loaded with a simple thrust of theblade, operation is much morerapid. In' continuous operation, for example, there are no longer anyempty positions which might formerly result because the operator couldnot get the blade inserted into the socketed cylinder during the time itwas exposed to him. Further, the gripping members will accept blades ofa considerable range of sizes and curvatures, so that it is no'longernecessary to have a separate set of tooling for every different size orpattern of blades. Items other than turbine blades can also be peened insuch equipment, and in some cases even with the same tooling rings,where the workpieces have sections suitable for gripping between therings.

It is therefore an object of this invention to provide apparatus forholding workpieces during a peening operation.

It is another object to provide apparatus for passing turbine bladesthrough a peening zone, masking the airfoil portions while exposing theroot portions to peening action.

Other objects and advantages will become apparent on reading thefollowing specification in conjunction with the accompanying drawings.

I BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERREDEMBODIMENT In FIGS. 1 and 2 there is shown an illustration of the deviceof the invention, with some of the proportions and the amount 1 ofrelative displacement of the rings exaggerated for clarity ofillustration. There is shown a vertical shaft 11 journaled inappropriate bearings (not shown). The drive means may be a motor 12drivingly connected to the outer ring by a belt 13, or the motor may beconnected to the shaft 11 by gearing or other suitable arrangement.There may also, be provided means for intermittent stop-motion so thatblades may pause briefly in line with the peening nozzles, shownschematically at 14.

The shaft 11 has mounted thereon a hub 16 having ribs or spokes 17extending radially therefrom and Supporting a barrel l8, coaxial withthe shaft and rotatable therewith. Surrounding barrel 18 and coaxialtherewith is a larger barrel 19, having its top edge 21 somewhat lowerthan the top edge 22 of barrel l8. Barrel 19 is supported by ribs 23extending radially from the exterior surface of barrel 18, providing anannular space 24 between the two barrels.

The top edges of ribs 23 are disposed in a plane on which rests a ring26 of a diameter intermediate between those of the two barrels, andextending upwardly to a level with the upper edge 22 of barrel 18. Thering 26 is keyed to the outer barrel by a plurality of fingers 27 (bestshown inFIG. 3) extending radially outwardly from the circumference ofthe barrel, and

resting in clevis members or yokes 28 extending radially inwardly fromthe outer barrel 19. This arrangement leaves ring 26 free to slide backand forth across ribs 23, but keyed to the turntable for rotationtherewith. Other means of supporting ring 26 may be satisfactory if itis desired to otherwise position ribs 23. For instance, the ring may besupported wholly by fingers 27 in the yokes 28. It will also beunderstood that the fingers and yokes may take forms somewhat differentfrom those shown; the yokes may be individual members, or may be acircular channel with slots cut in the vertical web for the fingers, orthe fingers may extend through holes in barrel 19.

The outer circumference of barrel 18 has a plurality of cushion grippingmembers 29 positioned thereon near the top and projecting slightly abovethe top edge 22 (best shown in FIG. 3). The gripping members may beformed of rubber or other suitable resilient material. The inner surfaceof ring 26 has an equal number of similar gripping members 31, pairedwith those of barrel 18 in opposed relationship.

Ring 26 is constantly biased toward one side of the turntable by thepressure of a pair of rollers 32 which idle against the exterior surfaceof the ring. Each roller is mounted on an arm 33 having a swivel joint34. Pressure is applied to the rollers by pulling the arms together witha turnbuckle 36, which is protected against damage by stray peeningmaterial by being enclosed within a tube, pipe, or other suitablehousing 37.

Pulling the adjustable arms together with the turnbuckle causes therollers 32 to bear harder against ring 26, thrusting it further offcenter, whereas loosening the turnbuckle allows the arms to separate andthe pressure to relax. The turnbuckle assembly is held to the adjustablearms 33 by seating its ends in clips 34 or other suitable detentsattached to the arms, and is demountable therefrom when it is desired toswing the rollers free of engagement with the ring 26.

The larger part of the turntable is enclosed within a peening cabinetformed of a flexible curtain, indicated schematically by the dashed line36. Such cabinets are known in the art, and may be formed of rubber,plastic, or the like. At the points where the turntable enters andemerges from the cabinet the curtain is formed into a plurality offlexible fingers or strips which are resiliently brushed aside by themoving equipment.

The slidable ring member 26 is normally biased toward the side of theturntable which protrudes outside the peening cabinet, at the left sideof the illustration in FIG. I. The spacing between the members 29 and 31of each pair of grips is therefore greatest at that point, which is theloading station. A workpiece 37, such as a turbine blade (as shown inFIG. 2) is thrust by the operator into the space between a pair ofgrips, which lightly engage the workpiece. The portion of the workpieceto be peened remains exposed above the turntable, and the portion to beshielded extends into the annular space 24 between the two barrels wherepeening material will not reach it. As the turntable rotates, the spacebetween gripping members 29 and 31 diminishes, holding the workpiecefirmly. The portion to be peened, such as the root portion of a turbineblade, traverses the peening zone past appropriately disposed andoriented peening nozzles 14. When the treated workpiece reappearsthrough the flexible curtain, the holding pressure of the grippingmembers has again relaxed, the operator removes the workpiece andinserts another. The speed of the turntable is governed to the desiredlength of peening time, having regard to the number of peening nozzlesto which the part will be exposed. if desired, the turntable may beoperated with an intermittent stop-motion, so that each workpiece has adwell time before one or more peening nozzles. The amount of relativemovement shown between the movable ring and its related barrel has beenmuch exaggerated in the drawing for clarity of illustration. In actualoperation, the spacing at the loading station is such as to allow readyinsertion or removal of a part, and at the opposite diameter, inside thepeening cabinet, the part is firmly held without undue distortion of thegripping members. It is possible to pressure bias the slidable ring inthe opposite direction, in which case the gripping members are mountedon the outside of the ring and paired with similar gripping members onthe inside of the outer barrel.

It will be apparent from the foregoing description that apparatus of thetype set forth is suitable for peening portions of workpieces of variouskinds and shapes, and that within reasonable limits workpieces ofdifferent sizes may be peened without a change of tooling.

What is claimed is:

1. Apparatus for shot-peening workpieces, comprising in combination aturntable having an outer barrel rotatable on a vertical axis, an innerbarrel coaxial and rotatable therewith, the two barrels defining anannular space therebetween, a ring member disposed between the twobarrels and having an axis parallel to but displaced from the barrelaxis, the ring being rotatable on its own axis and keyed to one of thebarrels for rotation thereby, a plurality of pairs of opposed grippingmembers mounted respectively on the ring and one of the barrels, eachpair of gripping members being adapted to hold a workpiece therebetween,one side of the turntable comprising a loading station where the spacingbetween members of a pair of gripping members is greatest to allowpositioning of a workpiece therebetween, such spacing progressivelydiminishing with rotation of the turntable to the side diametrallyopposite.

2. The combination recited in claim 1, wherein at least one shot-peeningnoule is disposed at a position circumferentially removed from theloading station, and the workpieces are rotated throu h the dischargezone of the nozzle.

3. The com ination recited in claim 2, wherein the axis of the ringmember is maintained displaced toward the loading station by pressureagainst the ring from the direction opposite the loading station.

4. The combination recited in claim 3, wherein the pressure isadjustably applied by a pair of idler rollers bearing against the ring,each of the rollers being mounted on a pivotable arm extending towardthe ring, the arms being connected by extensible means to govern thespacing therebetween and thereby vary the pressure of the rollersagainst the ring.

5. The combination recited in claim 4, wherein the gripping members areformed of resilient material, the mating members of each pair beingmounted respectively on the outer circumference of the inner barrel andon the inner circumference of the ring.

6. The combination recited in claim 5, wherein the gripping members arepositioned at the top of the turntable to hold a workpiece with theportion to be shot-peened protruding above the gripping members and theremainder of the workpiece disposed in the annular space between thebarrels and shielded by the barrels from peening material.

7. The combination recited in claim 4, wherein yoke members extendradially inwardly from the wall of the outer barrel, and fingers extendradially outwardly from the ring, the fingers being slidably positionedin the yoke members to key the ring to the outer barrel for rotationthereby.

1. Apparatus for shot-peening workpieces, comprising in combination aturntable having an outer barrel rotatable on a vertical axis, an innerbarrel coaxial and rotatable therewith, the two barrels defining anannular space therebetween, a ring member disposed between the twobarrels and having an axis parallel to but displaced from the barrelaxis, the ring being rotatable on its own axis and keyed to one of thebarrels for rotation thereby, a plurality of pairs of opposed grippingmembers mounted respectively on the ring and one of the barrels, eachpair of gripping members being adapted to hold a workpiece therebetween,one side of the turntable comprising a loading station where the spacingbetween members of a pair of gripping members is greatest to allowpositioning of a workpiece therebetween, such spacing progressivelydiminishing with rotation of the turntable to the side diametrallyopposite.
 2. The combination recited in claim 1, wherein at least oneshot-peening nozzle is disposed at a position circumferentially removedfrom the loading station, and the workpieces are rotated through thedischarge zone of the nozzle.
 3. The combination recited in claim 2,wherein the axis of the ring member is maintained displaced toward theloading station by pressure against the ring from the direction oppositethe loading station.
 4. The combination recited in claim 3, wherein thepressure is adjustably applied by a pair of idler rollers bearingagainst the ring, each of the rollers being mounted on a pivotable armextending toward the ring, the arms being connected by extensible meansto govern the spacing therebetween and thereby vary the pressure of therollers against the ring.
 5. The combination recited in claim 4, whereinthe gripping members are formed of resilient material, the matingmembers of each pair being mounted respectively on the outercircumference of the inner barrel and on the inner circumference of thering.
 6. The combination recited in claim 5, wherein the grippingmembers are positioned at the top of the turntable to hold a workpiecewith the portion to be shot-peened protruding above the gripping membersand the remainder of the workpiece disposed in the annular space betweenthe barrels and shielded by the barrels from peening material.
 7. Thecombination recited in claim 4, wherein yoke members extend radiallyinwardly from the wall of the outer barrel, and fingers extend radiallyoutwardly from the ring, the fingers being slidably positioned in theyoke members to key the ring to the outer barrel for rotation thereby.